Effect of Gibberellic Acid on Seed Germination of Onopordum nervosum Subsp. platylepis Murb

“The Mediterranean Basin, particularly Tunisia, is considered to be one of the planet’s biodiversity hotspots, due to the region’s high level of endemism”. Spontaneous plants, such as Onopordon nervosum subsp. platylepis Murb could be valorized and used as milk-clotting agent for cheese making in order to respond to an increasing demand of veg-friendly cheeses. O. nervosum subsp. Platylepis Murb is an endemic plant belonging to the Asteraceae family and growing particularly in north and central Tunisia. Cultivation and valorization of this plant is difficult because of seeds germination problems. Cypsela presents a high dormancy level. The cypselae were collected from Chott Meriem region (Sousse, Tunisia) and were tested for viability after 8 and 20 months of storage in laboratory conditions. Seeds collected in 2020 were germinated in Petri plates and in plug trays using increasing levels of gibberellins (GA3) from 0 to 0.1%. The highest germination rates 90% and 66.6% were obtained with 0.1% GA3 treatment in Petri plates and in plug trays tests, respectively. Comparing responses of seeds collected in 2019 and in 2020 to GA applications, results showed that while storage duration did not affect seeds viability, slight decrease in germination percentage was observed with the increase of storage duration. A maximum percentage of 97.7% was recorded with both 2019 and 2020 collected cypsela when treated with 0.075% GA.